Thread: Tikka action screws

Normally you apply separation force between the two parts, and turn the bolt/screw undone, or grind/cut the head off, and remove the two half's, and deal with the striped bolt after.
Seen as you are now going to need, an thread insert installed, consider dropping it off at a gun smith or machinist.
Now for sum free advise, buy sum antisieze, put it on every bolt and screw in steel, that does not spin round, at a great rate of knots, And yes I use it on my scope mounts and bases, shock and horror, you can use locktite, but the only thing worse than a striped thread is a striped alan bolt or torx head, grrrr.
Also torque on hardware is very different, between dry and lubed, a tiny bit of lube, on thread and the contact face on the head of the bolt, (antisieze is fine) allow a much smother torque, and prevent galling and false torques readings.
Know the difference between ft lbs, inch lbs and Newton meters, as well as thou and hundreds of a MM, there has been an awful pile of balls up's, over the years, getting them wrong. or assuming, the tools you used were one, when they were the other.